[Robbie] It's one of the most

exciting moments in any tennis match.

A player steps up to the base line,

maybe bounces the ball a few times,

and then smashes an ace past their opponent.

And while the pros make it look easy,

the tennis serve is actually an incredibly complex stroke.

Hitting a tennis serve effectively

is one of the hardest things in sports to do.

[Robbie] Even if you somehow master the mechanics,

there's also strategy to consider,

like whether it's your first or second serve,

where your opponent is standing,

and what your last serve was like.

Just like in baseball, where pitchers wanna avoid

throwing the same pitch over and over,

servers like to mix things up

keeping their opponents on their toes.

One thing that most serves have in common,

at least at the professional level,

is speed, lots of speed.

We're talking about serves that leave

the racket at 120, 130, even 140 miles per hour.

And the absolute fastest serves on record

reach into the 150's.

But is that as fast as we can go?

Today, we're gonna look at why serving a tennis ball

160 miles per hour is almost impossible.

To find out what it takes, I talked to

one of the biggest servers in the game.

Mechanics are critical.

Having good mechanics, having good flexibility,

allows you to kind of have that leverage

to make a ball really move.

[Robbie] Tested my form with a sports scientist.

We don't wanna be going straight up,

we actually wanna be going in that direction there.

[Robbie] Found myself on the receiving end

of some pretty humbling serves.

[laughs]

And even sacrificed a camera.

Look at this.

That is what 120 some odd mile per hour serve

will do to your GoPro.

The game of tennis has always had huge hitters.

In 1974 at a speed competition held at the U.S. Open,

Australian Colin Dibley was clocked

crushing a tennis ball at 148 miles per hour.

But that was in a competition designed

specifically for testing speed.

In match play, most players don't hit as hard as they can

'cause they also have to control where the ball goes.

Still, serve speeds have increased over the years.

Through the 80's and 90's the fastest serves on record

were in the 130's.

In the late 90's we saw the first serves in the 140's,

and in the early 2000's we saw them creep

into the 150's for the first time.

The fastest serve ever recorded?

That came in 2012, when Australian Sam Groth

was clocked serving a tennis ball at 163.7 miles per hour.

Now the Association of Tennis Professionals

does not recognize that serve,

and that's because Groth delivered it at what's called

a challenger event,

where the serve speed guns aren't subject to

the same standards as those on official tour events.

The fastest serve recognized by the ATP?

That was delivered by American John Isner,

at a speed of 157 miles per hour.

So what does it take to hit a serve that fast?

And what's keeping them from getting faster?

You wanna jump a little towards where you're serving.

That way the momentum of your body's kind of

helping you out with the power and all that.

[Robbie] Ulises Blanch is a 21-year-old pro

who can hit serves up to a blistering 138 miles per hour.

We visited him at the USTA National Campus

outside of Orlando to learn some fundamentals.

So like what's the first thing people learn

when they learn to serve, do you know?

Throwing the ball up. Getting that consistent?

Yeah trying to get that as consistent as possible.

Let's see if we can at least clear the net this time?

Hit it a little higher if you can.

[Robbie] As you can see, my form was terrible.

But with Blanch's help, I was at least able

to improve my serve speed.

77!

But it didn't take long for that pride to wear off.

So now Ulises is gonna try.

Remember 77 miles per hour is the speed to beat.

I'll keep that in mind, I'll try to do it.

[Automated Voice] 129.

He's casually hitting triple digits in his warm up.

And if you think hitting the ball that fast is tough,

just try returning it.

[laughs]

Look at it this way, for a 130 mile per hour serve,

you've only got about half a second to react.

For a split second every single time he serves it

and it's like no I got it, it's going here.

And then I don't have it at all.

Okay, so I definitely won't be joining

the ATP any time soon,

but I'd at least like to understand why my serve

is so much slower than Blanch's.

So what do you think is keeping me from serving

faster than 77?

I mean it's technique, all that is technique.

So here you are over on the left,

and then this is Ulises' serve on the right.

[Robbie] We recorded our session with cameras

from multiple angles,

and then asked USTA Performance Analyst Dave Ramos

to compare our mechanics.

Quite a bit of difference from one to the other.

Huge difference.

The biggest difference is how we store and release energy.

It all starts in our legs.

Blanch's are straight, but mine are bent.

That's because I'm using my lower body

to help throw the ball into the air.

That's very common actually for new servers,

to almost feel like they have to put some energy

into the toss.

[Robbie] Ramos says your arm is more than strong

enough to lob the ball on its own,

and involving your legs at this stage actually just

adds more complexity to your movement,

which can make your ball toss less consistent.

Now look at our hitting arms.

Blanch activates his by drawing it back

in one fluid motion.

My arm, it barely moves.

At the point of release,

our bodies could not look more different.

Look how open Blanch's chest is.

By rotating his hips and his shoulders,

he's already begun storing energy in his upper body.

This is called coiling, and I am really, really bad at it.

Just watch what happens in the next stage of the serve.

By the time the ball reaches its apex,

Blanch's upper body is so tightly coiled

his shoulders are pointing at the sky.

Mine are practically level with the ground.

You'll also notice that while we've both bent our knees

to store energy in our legs,

Blanch has shifted his weight in a way

that will allow him to leap not just up,

but forward towards the ball,

as he explodes out of his squat.

This allows him to transfer the power

that he stored in his leg upward, through his body

and into his racket by uncoiling his hips,

his torso, and finally his shoulders.

Right before impact, Blanch's arm is fully cocked

and the head of his racket is pointing right at the ground.

The result of a huge external rotation

in his right shoulder.

Just look how high his elbow is, relative to his hand.

My external rotation by comparison,

is basically non-existent.

Which brings us to the point of contact.

[Dave] You're basically looking for as close

to a straight line,

from the tip of the racket down to the hand,

to the elbow to the shoulder,

and then through the hips, and then out through the body.

So it looks pretty much like a straight line

where you can see.

On yours, you have a couple of segments.

[Robbie] Got all kinds of angles goin' on.

The good thing is you are centering the ball

which is pretty good,

but the tip of the racket comes down to the hand.

Then the hand goes down to the shoulder,

and then the rest of the body is one straight line.

[Robbie] Those zig-zaggy lines highlight breaks

in my kinetic chain,

the sequence of rotations that sum the forces

generated by my lower and upper body.

[Dave] K Go ahead. And the kinetic chain

is crucial for a high powered serve.

A very efficient kinetic chain energy transfer

means that whatever energy you can create

from your ground reaction forces,

nearly 100 percent of that gets shifted up

through the body, out into the ball.

[Robbie] That's Mark Kovacs, a sports scientist

who works with some of the hardest hitters in the world.

We visited his lab outside of Atlanta, Georgia,

where he covered me in sensors,

and had me serve on a pressure mat,

so we could pick apart my serve.

One of the first things we noticed

was my lack of force production.

Even if my technique had been perfect,

I just wasn't generating that much force with my legs.

Your peak force here is between 800, 900 newtons,

which is pretty normal for a recreational type player.

The pros, 50 percent more than that, many of them,

up at 1500, some of 'em even a bit higher than that.

[Robbie] Plus not only was I generating less force,

I was also putting that force in the wrong place.

[Mark] So you can see, looks like

a vertical jump right there.

So if we look on the screen,

that would be a standard looking vertical jump

if I was doing an NBA combine or NFL combine.

I'm actually reasonably happy with the position there.

But on a tennis serve, we don't wanna be going straight up,

we actually wanna be going in that direction there.

[Robbie] And finally, I wasn't rotating

my shoulders enough.

Remember, it's all about that coil.

You've got what we call an inefficient kinematic sequence.

It's all happening at once,

so you're not getting that benefit

or that summation of forces that we'd like to see.

An inefficient kinetic chain transfer

means that that 100 percent of ground reaction force

that you've produced,

you may only get 70 percent or 60 percent of that

into the ball.

That's a very inefficient model,

and that also potentially increases your injury risk

because you have to do more in the upper body.

As you can see, you also collapse right at the end,

which doesn't look very healthy there.

We're bent over, we're collapsing falling to the side.

I'm just keeping track of the adjectives

Mark has used to describe my form, we've got weak,

inefficient, and collapsing.

[laughs]

Again they're all fixable, that's the good thing.

Cool.

There's plenty of opportunity for improvement here

and that's what we like to see.

[Robbie] One thing I can't fix? My height.

For a tennis player you're not that tall.

So the net's a little higher for you,

so you can't really hit down on it.

[Robbie] And that makes a difference.

Reilly Opelka is one of the fastest servers

on the tour.

He's also tied for the tallest.

You know, being seven foot helps.

The main difference is the trajectory,

and the angle it's coming at is significantly higher.

So the way bounces off the court,

the peak height of it is foreign to a lot of players,

they're not used to seeing a seven footer

serving from that height,

and the ball coming from that angle.

You've gotta really look at some of those tall players

if you're looking at the absolute fastest servers.

The John Isner's of the world, Reilly Opelka's.

They're all six-seven and above.

[Robbie] You can actually graph that correlation.

Here's a chart of some of the fastest serves on record,

in relation to player height.

That line visualizes the relationship

between player height, and speed.

You don't need to be tall to hit hard,

but it definitely helps, in a couple concrete ways.

[Mark] You've got longer levers,

so you could store energy over a greater amount of time.

And it allows you to submit your forces

over a greater distance.

The second big thing is you've got a height advantage

from a geometry standpoint.

Six-foot-seven is what the estimated height is

for people that can actually hit down on a serve.

Anyone under about six-foot-seven,

actually is still hitting up on the serve.

So if you're hitting up on the serve,

you're fighting gravity.

If you're hitting down on the serve,

gravity's actually helping you.

[Robbie] But height isn't everything.

Part of developing a big serve is having

good coaching, good mechanics.

We've always been on top of my flexibility

through my shoulder, through my spine.

Good mobility, it's all critical.

I have a lot of players that are mid-six feet

that have very very fast serves,

you know Andy Roddick was an example.

Six-twoish range, and still has

one of the fastest serves of all time.

So it's not a one-to-one correlation,

but it is a predictor,

it's one of those predictors that the taller you are,

the higher the ceiling you have to have

a great and fast serve.

If you have someone with pure technique

nearly perfect technique, which Andy Roddick does have,

and you add height to it and the technique is maintained,

then for sure you're just gonna increase serve speed

from that standpoint.

So that's where the argument can be made

that we do have still a higher ceiling

for serve speed potentially.

[Robbie] So what drove those steady increases

in serve speeds in the 80's, 90's, and early 2000's?

And why aren't we seeing them today?

A lot of it has to do with technology

sort of being relatively consistent

over the last five years.

If there is a technology change going forward,

we could see a spike.

Over the decades, it's the evolution of the racket

that has probably had the single biggest impact

on serve speed.

For much of the 20th century,

wooden rackets dominated the game of tennis.

But in the mid-70's, manufacturers began experimenting

with materials like carbon fiber and resin,

to produce rackets with much bigger heads.

In the 1970's your standard wooden racket

had a surface area of about 70 square inches.

But the modern racket is well over 100.

And that increase in size had two effects,

number one, it made the sweet spot bigger,

which made the game a lot more approachable for amateurs.

[Dave] Typically the sweet spot is in the upper part

of this racket,

and it's maybe a little bit bigger than the size

of a ball.

And in modern rackets, it's quite a bit bigger,

but on a racket like this if you don't hit the racket

dead center in the middle of the strings,

it's not gonna respond or it's gonna be unstable.

[Robbie] But professionals didn't really need

a larger sweet spot.

And for them bigger rackets had a different effect,

the ability to put more top spin on the ball.

That's because more surface area means more room

for the ball to roll across the racket and gather spin.

Thanks to a phenomenon known as the Magnus Effect,

a ball hit with more spin dives towards the court

at a sharper angle once it clears the net.

Putting more spin on the ball allowed pros to

lower their risk of hitting out of bounds

when they hit harder.

The result? More powerful play, and faster serves.

Especially for bigger, stronger players.

Advances in string technology have also had

an impact on serve speed.

Where players used to string rackets with cow gut,

today's pros use some combination of polyester strings

that can be made fat, or thin, or round, or square-shaped.

And strung at a variety of tensions,

depending on the player's needs and style of play.

It's important to have just the right tension

because it gives you the ability to create power

without a lot of effort.

So if you string higher you're gonna have more control,

you string lower you have more power.

[Robbie] In fact a lot of players have

several rackets to choose from in a given match.

They'll use one for serving,

one for returning,

and a whole bunch of backup rackets

for anything that comes up.

I was sitting with a coach who was preparing

Serena Williams' rackets,

she uses 11 rackets in a match.

Because she has all the bases covered.

Players are incredibly sensitive to racket tension

and conditions.

And a lot of times it happens,

it changes as the match goes on.

If it gets more humid or if it rains,

or if the balls change a little bit,

they wanna have a lot of options.

[Robbie] The ball can effect serve speed too.

New balls tend to fly faster than old ones.

That's because balls lose pressure over time,

and the more you play with it, the fluffier it gets,

which increases drag.

Environmental factors can also impact your serve speed,

including whether you're playing on a hard,

clay, or grass court.

Court surface can play a bit of a role,

even though it's being measured in ball speed

and through the air.

What court speed does is it changes your strategy.

If you've got a really slow court,

you may not try to serve as hard.

You may be more strategic so it changes how people serve.

And then there's air density,

which is effected by things like altitude, humidity.

The higher elevation you're at,

and the more hot and humid the air,

the less resistance the ball experiences,

translating to faster speeds.

Conditions are everything.

I guarantee you you won't see a guy come to the French Open

on a slow clay court in Europe

when it tends to be a little cooler out, maybe rainy.

You won't see a guy serve over 150 there,

but if we do see a serve peak over 160,

I would think it'd happen somewhere on a hot

fast, hard court.

Somewhere like in Atlanta or Washington D.C.

So what have we learned?

Number one, if and when someone finally does

break into the 160's, officially,

they will almost definitely be incredibly flexible

in their hips, torso, and shoulders,

and be able to uncoil those elements

in the precise way necessary to translate power

from their legs, through their body, and into their racket.

They'll probably be swinging a cutting-edge racket

and hitting a brand new ball.

And odds are pretty decent that they'll be playing

on a hard court in hot, humid weather.

And they'll probably be tall.

The point is, no one can say for sure

when all of these variables from form and fitness

to height and equipment will align.

Or whether they will at all.

But until they do, keep in mind that

what the hardest hitters in the world are doing today,

is already almost impossible.

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